dreadfully adverb exceedingly UK,1697 Often used to imply or intensify a pejorative sense.
Dreadfully sorry / Dreadfully sorry[.] — The Who 5:15, 1973
But since the breakfast in Paris, those radical rive gauche pavement heaters have become dreadfully common patio heaters and you can’t move in B&Q without falling over one. — TheObserver, 29 June 2003